Machine-switching telephone system



,Filed Oct. 18, 1918 L POLIINKQWSKY MACHINE SWITCHING TELEPHONE SYSTEM ml 12 w uwm umll lg l,5@4l-,2@7

. L. POLINKOWSIKY MACHINE SWITCHING TELEPHONE SYSTEM Filed Oct. 18 1918 2 Sheets-Sheet 2 Mung j VLZ, L

//4 ve h/a V.

Patented Aug. 12, 1924.

tears? eerie.

LIIPA POLINKOWSKY, OF LONDGN, ENGLAND, ASSIGNO'R TO WESTERN ELECTRIC COM- PANY, INCORPORATED, F NEVI YORK, N. 1 A CORPORATIQN OF NEVJ YORK.

MACHINE-SWITCHING TELEPHONE SYSTEM.

Application filed October 18, 1918.

To all w/wm it may concern: v

Be it known that I, LIPA POLINKOWSKY,

a citizen of Russia, residing at 70 VVestbourne Terrace, Hyde Park, London, England, have invented certain new and useful Improvements in Machine-Switching Telephone Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to machine switching telephone systems and more particularly to systems wherein in addition to the usual or ordinary service provided for the interconnection of the subscribers stations 5 of an exchange network the subscribers lines of the machine switching telephone systems may be also connected over a manual switching section with the toll board.

A feature of the invention is the provision of means associated with the incoming end of a trunk line extending between a toll board and a manual switching section, responding to ringing current sent from the toll board over the trunk line after the con nection has been further extended to the wanted line to connect the wanted subscribers line with a source of ringing current after the lapse of a predetermined length of time.

A further feature of the invention is the provision of means associated with the incoming end of a trunk line which, in response to the first ringing cu'i'rent over the trunk line, removes the condition of the circuit for non-disturbing listening and connects the wanted line with a source of transmission current supply and supervisory means, and, after a lapse of a given length of time, connects the wanted line with a source of ringing current should the supervisory means remain unoperated.

A still further feature of the invention is the provision of means comprising a set of relays operating in succession and responding to the first depression of the ringing key on the toll board to provide the creation of the condition at a terminal of the wanted line which causes the release of a local connection, the removal of the condition of the circuit for non-distributing listening and the delayed connection of the bringing current with the wanted line.

Certain other inventive features herein disclosed are not claimed herein but form the subject matter of an application for patent Serial No. 258,683.

of Gerald Deakin serial number 263,884, filed November 23, 1918, and are claimed therein.

In the accompanying drawings:

. Figure 1 shows the arrangement of cirsuits and apparatus associated with the incoming end of a trunk line extending from a toll board to a manual switching section.

Figure 2 shows the toll operators position.

Fi 3 illustrates part of a machine switching section engaged in a local connection.

The system will be best understood from a description of the operation thereof.

The switching section is connected in the well-known manner over an order wire with the toll board, on which the toll cords are provided with supervisory relays operated over the sleeves of the jacks of the trunk lines. When the order wire key 251 is de pressed and the operator at the switching section receives instructions, she lifts the plug of a free cord from its seat, tests the line and inserts the plug into the jack of the wanted line. The subscriberline remains thereby free for local connections until made busy from the toll. board.

In. a large exchange in which multiple jacks are used at the switching section, the operator through testing ascertains whether or not the line is engaged in another toll. connection. She can also ascertain this fact when testing one of several lines leading to a private branch exchange. After the plug 210 is brought into the jack av circuit is established for the energization of relay 211 over the cut-off relay 207 of the subscriber line, the sleeve 209 of the jack, the sleeve of the plug 210, both windings of relay 211 in series and the secondary winding of the busy tone coil 212 to ground. The condenser 213 around the left. hand high resistance winding of relay 211 enables the creation of a busy tone at the sleeve 209 of the jack so that the subscriber line now appears engaged in a toll connection. Relay 211 closes over its front contact a circuit for the energization of the left hand winding of relay 21 which disconnects on its left hand back contact the testcircuit and provides over its left hand front contact a bridge to the sub scriber line containing the left hand windings of the repeating coil 215 in series with a small condenser 216. Over the right hand front contact of relay 214 and the contact of the plug seat switch 218 a circuit is provided for the right hand winding of relay 214 and the winding of relay 217, which is thereby energized and in opening its back cont-act dis connects the winding of the slow operating relay 219. The guard lamp 220 lights in a circuit over resistance 221 and right hand front contact of relay 214. After the plug 250 is inserted into the jack of the assigned trunk line at the toll board, relay 253 is energized in a circuit over the sleeve of the jack and clearing out relay 254. A circuit is then provided over the third wire of the trunk line including relay 255 at the toll board, the right hand low resistance winding of relay 222 and the back cont-act and armature of the supervisory relay 231 at the cord of the switching section. Both relays 222 and 255 are energized. Relay 255 provides a shunt around the high resistance winding of relay 258 so that relay 254 is energized and connects the clearing out lamp 252. Relay 222 provides over its front contact and a. contact of the plug seat switch 218 a shunt around the lamp 220.

The toll operator in depressing the listening key 256 connects her telephone in bridge to the trunk line and .ascertains, whether or not the wanted subscri'bers line is engaged in a local connection which beforehand remains undisturbed, the size of the condenser 216 being so selected that the bridge does not interfere with the local connection. The toll operator is also able to conununicate with the subscribers and to invite them to restore the receivers on the hooks. When the toll operator is ready to establish the through connection she depresses the ringing key 257 and sends a ringing current over the trunk line. Relay223 is thereby energized and provides a circuit for the energization of the right hand winding of relay 224 over right hand back contact of relay 219 and front contact of relay 223. Over the right hand front contact of relay 224 a circuit is then established for the energization of relay 225 which brings the comparatively large condenser 226 and both windings of the supervisory relay 231 in bridge to condenser 216. The sleeve 209 of the jack of the subscribers line is connected with ground over the sleeve of the plug 210 the left hand front contact of relay 224 and the left hand back contact of relay 219 whereas through the opening of the left hand back contact of relay 224 a circuit is established for the left hand winding of relay 224 and the winding of the slow operating relay 227 the circuit including the resistance 228 and the right hand front contact of relay 214. Relay 227 after closing its front contact provides a shunt around the winding of relay 217 so that this relay is slowly de-ene gized and in closing its back contact provides a circuit for the energization of the slow operating relay 219. In the opening of the left hand back contact of relay 21.9 the direct connection with ground of the sleeve of the jack is removed, whereas in closing the left hand front contact of relay 219 a shunt around the high resistance winding of relay 211 is maintained over the left hand front contact of relay 224. The sleeve 209 of the jack is now maintained busy over the right hand low resistance winding of relay 211. At the right hand back contact of relay 219 the operating winding of relay 224 is disconnected, while relay 229 is energized in a circuit including b ack contact of relay 231, right hand front contact of relay 219 and front contact of relay 223. Relay 22$ disconnects on its back contacts the left hand windings of the repeating coil 215 and the relay 231 from the subscribers line and connects the line to a source of ringing current.

The connection of the sleeve 209 of the ack direct to ground during the time relay 224 is energized, relay 217 is de-euergizcd and relay 219 is energized removes temporarily the potential at the test terminals of the subscriber line in the automatic exchange so that if the line is engaged in a local connection this connection is rel ascd. This relcase takes place in a manner similar to that shown and described in applicants (Io-pending application, Serial Number 251,003, filed August 27, 1918, through the de-energization of the relays 201 and 202 by the direct connection to ground of the test terminal. 204, resulting in the operation of sequence switch 200 and the release of the instrumentalities engaged in a local connection. The subscribers line is automatically made busy at the switching section and a local connection is automatically relmscd when the toll operator depresses the first time the ringing key 257 usually provided on her board; it follows that the toll operator has not to fulfil any special operation except to depress the ringing key. Though the ringing current serves as agent for the forced release of a local connection, the disconnection takes place locally over the sleeve of the jack. In order that the ringing current will not produce a sound audible to the subscriber should he listen into his telephone at the moment the operator depresses the ringing key, the sending of the ringing current is delayed until the SUPGI'VlSOIy relay 231 has had ample time to become energized over the subscribers line.

lVhen the toll operator restores the ringing key 257 relay 223 is de-energized and in consequence also rclay 229. The supervisory relay 2231 is again connected over the back contacts of relay 229-with the subscriber line. hen the subscriber removes the receiver from the hook, relay 231 is energized and the shunt around the high resistance winding of relay 222 is opened. lelay 255 is thereby de-energized and in opening the tit shunt around the winding of relay 253 causes the de-energization of relay 254 which disconnects lamp 252. When the subscriber restores his receiver on the hook, lamp 252 lights before the toll operator. To re-ring the subscriber the toll operator has to depress ringing key 257 so that relays 223 and 229 are energized. After the plug 250 is withdrawn at the toll board from the jack of the trunk line, relay is de-energized and opens the circuit of relay 222 which is then de-energized and removes the shunt around lamp 220. The operator at the switching section then withdraws the plug from the jack of the subscribers line. After the plug sea-t switch 218 is opened the relays 214, 224:, 219, 225 and 227 are deenergized and lamp 220 is extinguished.

If a plug is erroneously brought into the jack of a trunk line which has not been assigned and relay 222 is energized the guarding lamp 220 lights in a circuit over :t'ront contact of relay 222, resistance 230 and right hand back contact of relay 214.

hen the operator at the switching section finds that the wanted line is engaged in another toll connection she inserts the plug of the assigned trunk line into a busy jack 205 whereby relays 211 and 21.4: are again energized and the operator at the toll board in depressing listening key 256 perceives a busy signal from the busy tone coil 206.

\Vhat is claimed is 1. A telephone exchange system, comprising a toll board, manual switching sections and machine switching sections, calling and called lines terminating therein, trunk lines, a ringing key in said toll board, and means in said manual switching sections for causing the application of ringing current over said trunk lines to a local line in said machine switching sections by the operation of said ringing key after a substantial interval only.

2. A telephone exchange system comprising a toll board, manual switching sections, machine switching sections, calling and called lines, trunk lines, a ringing key in said toll board, and means in said manual switching sections comprising a plurality of relays operated in succession and adapted to create a substantial interval of time between the operaton of said ringing key and the application of ringing current to a local line in said machine switching sections.

3. A telephone exchange system comprising a toll board, subscribers lines, machine switches for establishing connections be tween said lines, a trunk line, means for extending a connection from the toll board over said trunk to a called subscribers line, a controlling device at the toll board, means responsive immediately to the operation of said device for releasing said machine switches when the same are engaging the called line, and means responsive after the lapse of a predetermined interval following the operation of said device for applying ringing current to the called line.

4. A telephone exchange system compris ing a toll board, manual switching sections, machine switching sections, calling and called lines, trunk lines, a ringing key on said toll board, and means in said manual switching sections for placing electrical conditions upon the trunk line leading to oneof said machine switching sections adapted to cause after a predetermined period of time the release of a local connection existing thereat upon the operation of said ringing key. 1

5. A. telephone exchange system comprising a toll board, manual switching sections, machine switching sections, calling and called lines, trunk lines, supervisory means in said manual switching sections, a ringing key on said toll board, means at said manual switching sections responsive to the operation of said ringing key for releasing a localconnection at said machine switching sections over one of said trunk lines and connecting said line to said supervisory means for a definite period of time, and in event of non-operation of said supervisory means for applying ringing current to a called line at said machine switching section released from. said local connection.

In witness whereof, I hereunto subscribe my name this 16th day of August, A. D.

LIPA POLINKOWVSKY. 

